1. Technical Field
The present invention relates to a broadcast receiving apparatus and a channel changing method in a broadcast receiving apparatus.
2. Related Art
In digital broadcasting using a set-top box, which is a broadcast receiving apparatus, program data on each channel is efficiently compressed according to for example a moving picture experts group (MPEG) coding standard, and programs corresponding to a plurality of channels are multiplexed based on digital modulation schemes for each transmission medium, and are transmitted.
Accordingly, the digital broadcasting system can broadcast several tens to hundreds of channels without using a number of repeaters, unlike an analog broadcasting system.
In other words, the digital broadcasting system greatly improves frequency use efficiency compared to the analog broadcasting system, thereby solving a problem of lack of broadcast channels.
In addition, the digital broadcasting system enables special pay broadcasting and plural use of bidirectional service broadcast software, and thus provides an opportunity for the broadcast industry to develop into a multimedia industry.
For these reasons, the digital broadcasting system has expanded from satellite broadcasting to cable and terrestrial broadcasting, and has been viewed as a next generation of broadcast technology.
However, the digital broadcasting system experiences a delay after channel selection due to digital broadcast signal processing, digital content protection, bidirectional application, and the like.
This phenomenon does not occur in the analog broadcast system, and makes digital broadcasting viewers uncomfortable. Digital cable broadcasting, digital terrestrial broadcasting and digital satellite broadcasting home to take such a long time upon channel selection, and it is known that digital cable broadcasting needs a longer channel selection time compared to other broadcast media.
The long channel selection time in the digital broadcasting system is caused by the tuning time for identifying physical channels, a process for determining whether channel reception is restricted to protect content, and a decoding process for logical channel identification.
In particular, in the process for determining whether channel reception is restricted to protect the content, when a selected broadcast program needs to be descrambled, broadcast data has to be descrambled. The broadcast data relates to the broadcast program selected by a user from the totality of broadcast data received from a broadcasting providing apparatus.
The broadcast data is descrambled according to descrambling control information generated by parsing program association table (PAT)/program map table (PMT) information included in a received channel broadcast signal.
However, whenever a user selects a broadcast program, a large amount of time is consumed in generating descrambling control information for the selected broadcast program, and thus much time is consumed in channel selection.